Embodiments of the present specification relate generally to inspection of a component and more particularly to a system and method for detecting defects in the component.
Typically, aircraft engines include one or more components that are made of nickel super alloys with thermal barrier coating (TBC) ranging from 6 mils to 15 mils. In one example, the components may be hot gas path components, such as high pressure turbine (HPT) blades or turbine buckets. During operation of the engines, these components may be subjected to stress or centrifugal force, which may cause cracks or other defects in the components. These cracks may occur below the TBC and hence, the cracks may not be visible to a user/inspector. Moreover, the cracks on these components may lead to a structural malfunction of the engine and may substantially damage the engine.
Conventionally, the components are either visually inspected or a fluorescent penetrant inspection (FPI) method is used to detect the cracks. As the cracks are underneath the TBC, it would be difficult for an operator to visually identify the cracks without removing the coating from the components. Also, the FPI method requires the TBC be removed from the components before inspection. Further, after inspection, the TBC is recoated prior to putting the components back in service. Removing the coating and recoating the components may substantially increase the cost associated with inspection of these components. In some cases, even though the components may not have developed cracks underneath the TBC at the time of inspection, however, since visual identification of presence or absence of such cracks is not feasible, the coating may be removed nevertheless for inspection. Hence, even if the cracks are not present underneath the TBC, the TBC needs to be removed and subsequently recoated, which in turn increases maintenance cost of the components. Moreover, both the visual inspection and the FPI method requires a trained operator to inspect the components and make a decision to scrap the components or send the components for repair.